xtensa: add static function tracer support

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

3 files changed, 55 insertions, 0 deletions

diff --git a/arch/xtensa/kernel/Makefile b/arch/xtensa/kernel/Makefile
index 1e7fc87a94bb..f90265ec1ccc 100644
--- a/arch/xtensa/kernel/Makefile
+++ b/arch/xtensa/kernel/Makefile
@@ -11,6 +11,7 @@ obj-y := align.o coprocessor.o entry.o irq.o pci-dma.o platform.o process.o \
 obj-$(CONFIG_KGDB) += xtensa-stub.o
 obj-$(CONFIG_PCI) += pci.o
 obj-$(CONFIG_MODULES) += xtensa_ksyms.o module.o
+obj-$(CONFIG_FUNCTION_TRACER) += mcount.o
 
 AFLAGS_head.o += -mtext-section-literals
 
diff --git a/arch/xtensa/kernel/mcount.S b/arch/xtensa/kernel/mcount.S
new file mode 100644
index 000000000000..0eeda2e4a25e
--- /dev/null
+++ b/arch/xtensa/kernel/mcount.S
@@ -0,0 +1,50 @@
+/*
+ * arch/xtensa/kernel/mcount.S
+ *
+ * Xtensa specific mcount support
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2013 Tensilica Inc.
+ */
+
+#include <linux/linkage.h>
+#include <asm/ftrace.h>
+
+/*
+ * Entry condition:
+ *
+ *   a2:        a0 of the caller
+ */
+
+ENTRY(_mcount)
+
+        entry   a1, 16
+
+        movi    a4, ftrace_trace_function
+        l32i    a4, a4, 0
+        movi    a3, ftrace_stub
+        bne     a3, a4, 1f
+        retw
+
+1:      xor     a7, a2, a1
+        movi    a3, 0x3fffffff
+        and     a7, a7, a3
+        xor     a7, a7, a1
+
+        xor     a6, a0, a1
+        and     a6, a6, a3
+        xor     a6, a6, a1
+        addi    a6, a6, -MCOUNT_INSN_SIZE
+        callx4  a4
+
+        retw
+
+ENDPROC(_mcount)
+
+ENTRY(ftrace_stub)
+        entry   a1, 16
+        retw
+ENDPROC(ftrace_stub)
diff --git a/arch/xtensa/kernel/xtensa_ksyms.c b/arch/xtensa/kernel/xtensa_ksyms.c
index 42c53c87c204..d8507f812f46 100644
--- a/arch/xtensa/kernel/xtensa_ksyms.c
+++ b/arch/xtensa/kernel/xtensa_ksyms.c
@@ -124,3 +124,7 @@ extern long common_exception_return;
 extern long _spill_registers;
 EXPORT_SYMBOL(common_exception_return);
 EXPORT_SYMBOL(_spill_registers);
+
+#ifdef CONFIG_FUNCTION_TRACER
+EXPORT_SYMBOL(_mcount);
+#endif